I heard that UK mains voltage was reduced to harmonise with Europe.. if true when did this happen and what is it..?
I have a relay with a coil voltage of 220 to 230V 50-60Hz which replaces an old one (240V/50Hz).
No it isn't, and years ago. What happened was the voltages were changed on paper, but nothing actually changed in the wires...
That'll be fine.
It was reduced on paper only:
- the old voltage was 240/415 V ±6% (226-254 V for single-phase) - harmonised voltage is 230/400 V +10/-6% (216-253 V ditto)
The new tolerance was supposed to change to ±10% (207 V min.), but this seems to have been indefinitely postponed.
The actual supply voltage has not been changed (no-one's gone around adjusting taps on transformers) and the DNOs still work to 240/415 V nominal, even when building new parts of their networks, AIUI. Filament lamps for the UK market are still made for 240 V operation.
Nevertheless for wiring design purposes: voltage drop, fault current & disconnection time calculations you should now use 230/400 V as the Uo/U value.
Anything with a rating which includes 230 V should be OK.
thanks.. I thought it might be a reason why the old relay does not work: I guess not.
In typical EU fashion the voltage was officially harmonised to 230V but then all countries were allowed a tolerance of +/- 5% ( or maybe
10% ?) so that nothing actually changed in practice.
But does the change mean that somebody out in the sticks who finds that their supply often drops to 220V will be stuck with it, but in days of yore the Electricity Board would have had to fix it somehow?
No. They merely change the tolerances. My mains is currently at 242.8v ;-)
Relays are about the most tolerant of electrical devices.
Not necessarily - the "harmonisation" down to 230v gives the suppliers a little more leeway where voltage levels are concerned, so if you happen to have some picky equipment it may not work if your supply is now 230v +10% / -6% (i've heard of instances like it in the past)
Yes, but bear in mind that that the minimum voltage (216 V) should be maintained up to the full current rating of the supply, generally 60 or
100 A. If the voltage drops below 216 when you apply a heavy load then complain (and complain, and complain...).
Shhh !
On Thu, 20 Dec 2007 12:59:21 +0000 someone who may be DIYdisaster wrote this:-
Just in case anybody assumes that a tolerance is some nasty EU idea, there was one before the UK joined what is now the EU.
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